This project proposes to study the chain cleavage and other multi-enzyme systems of the ovary and human placenta including: 1. Inhibition of the side chain cleavage enzyme in animals and humans in various physiological and pathological states. 2. Purification of the components of the electron transport chain and reconstitution of the system. 3. The stoichiometry and kinetics of the side chain cleavage reaction. 4. Sites and mechanisms of inhibition by various enzyme inhibitors. 5. Roles of electron donors and trophic peptides in the connrol of steroidogenesis. BIBLIOGRAPHIC REFERENCES: Uzgiris, V.L., McIntosh, E.N., Graves, P., and Salhanick, H.A. Implications of Ligand Modified Spectra of Cytochrome P-450 Associated witt Pregnenelone Synthesis in Mitochondira from Corpus Luteum. In Cooper, D.Y. and Snyder,R. (ed.) Cytochromes P-450 and b5, Plenum Press, N.Y., pp. 209-223. 1975.